Detection blind spots: non-standard file formats in malicious email campaigns | Kaspersky official blog
Brief
Threat actors are constantly developing new attack schemes — from OAuth token theft to attacks on AI agents — but the classics never quite leave their playbook. On any given day, an employee may receive malware attached directly to an email, or lying in wait behind a link embedded in an email.
Making these attacks succeed still requires a degree of creativity, and in recent years attackers have increasingly adopted exotic file formats. Users don’t perceive these formats as dangerous; more importantly, many EDR and email security solutions skip scanning them entirely. Yet they’ve proven highly effective for deploying malware or harvesting credentials.
Below are the file types that may be blind spots in your organization’s detection strategy — despite being observed as used in real-world attacks.
Disk images
This is the broadest and most dangerous attachment category.